1. Field of the Invention
The present invention relates to magnetic heads, magnetic head gimbal assemblies, and magnetic recording and reproducing apparatus, in which a three terminal magnetoresistive element or the like is used, and magnetic memory devices which are used for magnetic recording/reproducing switching devices.
2. Description of the Related Art
For use as reading elements of magnetic heads which are used in high-density magnetic recording and reproducing apparatus or recording elements of magnetic memory devices, Current in Plane, Giant Magnetoresistance (CIP-GMR) elements which allow current to flow in plane across layers and tunneling magnetoresistive elements have been proposed. The former magnetoresistive elements are described in Japanese Unexamined Patent Publication No. Hei 4-358310 and the latter magnetoresistive elements are described in Japanese Unexamined Patent Publication No. Hei 10-4227.
These previous magnetoresistive elements have limitations in increasing magnetoresistivity. In order to enhance such elements so that they make higher outputs, it is necessary to increase their magnetoresisivity by adding new material or function. In terms of material, to increase the magnetoresistive element output is achieved by application of highly spin-polarized materials typified by half metal ferromagnetic material
In Japanese Unexamined Patent Publication No. 2001-202604, the following approach is described. The magnetoresistance of a tunneling magnetoresistive element is increased by providing a highly polarized spin injection layer adjacent to a magnetoresistive element of a ferromagnetic tunneling type and injecting highly spin-polarized electrons into the magnetoresistive element. However, the above Publication 2001-202604 as an example of disclosed art to which the invention pertains did not disclose an adequate magnetoresistive structure including terminals, electrodes, and power supply elements which are essential components around a reading element for a magnetic head or magnetic head gimbal assembly and magnetic recording and reproducing apparatus and disclosed nothing about increasing giant magnetoresistance. Moreover, the above approach involves a problem of noise that cannot be reduced sufficiently if the resistance of the magnetoresistive element is on the same level as the previous similar elements.
To reverse the magnetization direction in a recording layer of a magnetoresistive element in previous magnetic memory devices, the use of a magnetic field produced by the current flowing through a bit line and a word line has been proposed. However, the following problems with this method have been presented: complex wiring is a bottleneck in high-density integration and applying a magnetic field to a locally targeted cell is difficult.